Police officers at the scene of the shooting at Sparks middle school. Photograph: David Calvert/Getty Images

A US middle school teacher who served two tours with the National Guard in Afghanistan has been hailed as a hero for trying to protect students from a shooting witnessed by up to 30 children.Police said a student at Sparks middle school was the lone gunman whoinjured two classmates, killed himself and took the life of the 8th-grade maths teacher, Michael Landsberry."We have a lot of heroes today, including our children … and our fallen hero, an amazing teacher," said Pedro Martinez, the Washoe County school district superintendent.On the school website Landsberry had posted a picture of a brown bear and the message: "I have one classroom rule and it is very simple: Thou Shall Not Annoy Mr L."Geno Martini, the Sparks mayor, said Landsberry, 45, who was married with two stepdaughters, had served two tours in Afghanistan with theNevada National Guard and was well known in the school community. "He proudly served his country and was proudly defending the students at his school," he said.Sparks is a city of 90,000 just east of Reno, Nevada. Students were filing off buses and reuniting with friends after a weeklong holiday when the gunfire began.Authorities did not provide a motive for the shooting, and it is not known where the boy got the gun. The two wounded students, both 12, were in a stable condition. One was shot in the shoulder, and the other in the abdomen.Investigators were trying to piece together the chain of events that began around 7.15am on Monday, 15 minutes before classes were to begin for 700 students in the 7th and 8th grades."The best description is chaos," said the Reno deputy police chief Tom Robinson. "It's too early to say whether he was targeting people or going on an indiscriminate shooting spree."The mayor also praised the quick response from police officers who arrived at the scene within three minutes of the initial 911 calls to find the gunman with a self-inflicted gunshot wound to the head.Students from the middle school and neighbouring elementary school were taken to the nearby high school, and classes were cancelled. The two schools will remain closed for the week.

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